1. Field of the Invention
This invention relates generally to gun-type, power fluid fuel burner-fired hot air furnaces, and more particularly to a condensing mode furnace of that type.
2. Description of the Prior Art
Gun-type, power fluid fuel burner-fired hot air furnaces conventionally comprise a gun-type power burner, such as an oil or gas burner; a heat exchanger for extracting heat from the products of combustion of the burner and having a combustion chamber therein which communicates with the heat exchanger and into which the burner fires; an exhaust passage for carrying the products of combustion from the heat exchanger to an exhaust flue, an air passage for carrying a flow of air over the heat exchanger to a hot air outlet thereby to extract heat from the heat exchanger; and a blower for causing a flow of air through the air passage.
Condensing mode furnaces are known which include a condenser for condensing water out of the products of combustion to reduce the stack temperature and thereby increase the efficiency of the furnace.
Conventional gun-type, power fluid fuel burner-type furnace systems typically include a thermostat for sensing the temperature in the space to be heated, and a furnace control including a fan and limit switch. Closing of the thermostat contacts initiates operation of the burner followed by initiation of operation of the blower by the fan switch. Opening of the thermostat contacts terminates operation of the burner and the fan switch thereafter terminates operation of the blower.